Fremgangsmåte og apparatur for å håndtere fluider i løpet av en operasjon med undersjøisk topphull eller riserløs boring

An apparatus and method for handling drilling fluids during a subsea top hole or riserless drilling operation is described. The apparatus (202) is configured to be located subsea and comprises a body (204) which defines a longitudinal throughbore and has a first upper end (210) configured to receive a drill string (214) from a subsea environment. A second lower end (216) of the body (24) receives drilling fluids from a wellbore, and an outlet (218) is coupled to a conduit (220) to provide a flow path for conveying drilling fluids circulating through the apparatus to a location displaced from the body (204). A cleaning subsystem (234/236) removes contaminants from a drill string (214) passing through the apparatus (202) and into the subsea environment.